Prior art solutions utilize filtering and a detection threshold for detecting the heart rate. In filtering the frequency band of the received signal is limited so that preferably only the heart rate signal passes through the filter. Furthermore, when the heart rate is calculated, only pulses which have a sufficiently high amplitude and exceed (or are below) the detection threshold are taken into account.
The disadvantages of the prior art solutions include the fact that they do not take the different forms of the QRS complex the heart rate into account, even though different persons may have very different QRS complex widths and wave forms. This can also easily lead to incorrect heart rate detection especially if there is interference in the environment. By adapting the detection method and measuring device to each person's own QRS signal, heart rate detection and wave form recognition can be improved and made more reliable.